Clinical Studies On Prevention Of Early Posterior Dislocation After Hip Arthroplasty

Objective: With the prosthesis, prosthesis dislocation has become thesecond common complications after hip arthroplasty. Dislocation greatlyimprove the patient’s quality of life, showed the hip pain, restricted movementand double lower limbs length changes and symptoms. Normally, there is acertain range of motion between the femoral hip prosthesis and acetabularliner, which almost close to the full value of the hip anatomy and physiology.Posterior dislocation is the most common conditions of dislocations, when thehip flexion, adduction and internal rotation, then the prosthesis neck hit thefront edge of the acetabular, which caused the femoral head emerged from theliner.The hip capsule and short external rotators are the import rear stablestructure of hip joint. Joint capsule is usually irregular structure whichcomposed of dense fibrous tissue, There are three major (ligament) thickenedareas, namely spiral, oblique and arched toward. There are many externalrotation muscles in hip joint, such as piriformis, obturators, gemellus,obturators, quadratus femoris and gluteus maximus. These muscles are locatedbehind the hip vertical axis, and their contraction will cause femoral rotation,so repair these muscles can significantly reduce the risk of dislocation.In the previous study, Methods for the treatment of hip dislocation afteroperation does not have a uniform standard. Treatment options include closedreduction and surgical intervention, and repair the joint capsule and externalrotators can effectively reduce the rate of hip dislocation after hip arthroplasty,and it has certain advantages to reduce the degree of recurrent dislocation afteroperation compared with conservative treatment. Now, repair the joint capsuleand external rotators can benefit most patients whom has received the hiparthroplasty, especially in elderly patients, which has been considered the gold standard for treatment of posterior soft tissue instability. In the past literature,no reports that the use of anchor repair piriformis muscle. With improvementsin surgery and doctor’s knowledge of the hip joint, fixed anchors have becomean indispensable restoration. The purpose of this study was to investigate theclinical significance and operation method of repairing joint capsule andexternal rotators in different positions, and provide evidence for preventing theearly dislocation after hip arthroplasty.Methods: Between March2011and March2013, random sample of103patients which underwent primary hip arthroplasty, and were divided into3groups(A、B、C), the number in each group was34,32and37respectively.There was no signiicant diference in gender, age, cause of injure, diseaseduration, type of fracture, combined medical disease, or prosthesis selectionamong3groups (P>0.05). The piriformis ending point of each group wereselected in the gluteal muscle tendon, the greater trochanter and piriformisfossa. Using the method of suturing to the gluteus medius tendon in group A,and the others use the method of anchor fixation to repair the retention of theposterior capsule and short external rotators. There was signiicant differencesin early hip dislocation rate after operation and hip internal rotation range atdifferent angle during operation (P＜0.05).Results: Postoperative hip dislocation occurred in1,0and0cases ofgroups A, B and C respectively. When flexions of hip and knee joint were90°and hip adduction was0°in each group patients, there was signiicantdiferences in range of hip internal rotation among three groups, showed asgroup C<B<A（P＜0.05）；When flexion of hip and knee joint was50°and90°espectively, and hip adduction was30°, there was signiicant diferences inrange of hip internal rotation among three groups, showed as group C<B<A（P＜0.05）; When flexion of hip and knee joint was80°and90°espectively, andhip adduction was30°, there was signiicant diferences in range of hip internalrotation among three groups, showed as group C<B<A（rank sum test:P＜0.05）. There was no signiicant diferences in range of hip internal rotationwhen flexion of hip and knee joint was30°,90°, and hip adduction was30° espectively（P＞0.05）。Conclusion: By the three methods of repairing the joint capsule andexternal rotators after hip arthroplasty, methods of group B and C can reducethe rate of early dislocation. The method of group C not only can fixpiriformis muscle in original position, but also has certain advantage inreducing hip internal rotation range.